Supercritical fluids are known to exhibit a variety of properties, including enhanced solvent properties. Mc Hugh, Krukonis, Supercritical Fluids: Principles and Practice (Butterworths, Boston, Mass., 1986) co-authored by one of the inventors of the present invention, is an extensive overview of the properties and applications of supercritical solvents. Supercritical fluids are effective at separating low vapor pressure oils, fractionation of polymers, preparation of submicron particles of pharmaceutical compounds and explosives, cholesterol extraction from eggs, and other applications in the chemical and petroleum industries.
With respect to cleaning items such as electronic circuit boards and precision parts, processes relying upon chlorofluorocarbons (CFC's) are known in the art. However, CFC's are not acceptable because of the environmental and health adversities associated therewith. CFC's are a documented source of ozone depletion. For this reason, alternatives to CFC processes must be developed.
One alternative is the use of supercritical carbon dioxide for the removal of organic and oil-based contaminants. Processes relying upon supercritical carbon dioxide are known in the art. However, the art recognized methods are not sufficient insofar as they do not adequately clean porous materials or materials which exhibit tight clearances between adjoining components. Similar problems exist with swellable materials, such as polymers from which undesirable components must be removed.